1. Field of the Invention
The present invention relates to a receiving terminal in a wireless communication system. More particularly, the present invention relates to an apparatus and method for removing a Direct Current (DC) offset at a receiving terminal in a wireless communication system.
2. Description of the Related Art
In a wireless communication system, a Radio Frequency (RF) receiver of a receiving terminal down-converts a signal received through an antenna and amplifies the received signal. The RF receiver includes analog elements such as a filter, a mixer and an amplifier. Accordingly, the receiving terminal undergoes a signal distortion due to the imperfection and isolation of the analog elements constituting the RF receiver. For example, the receiving terminal undergoes a signal distortion due to a DC offset.
The DC offset degrades the digital demodulation performance of the receiving terminal, thus degrading the Signal-to-Noise Ratio (SNR) of the receiving system. Accordingly, the receiving terminal must remove the DC offset. For example, the receiving terminal may remove the DC offset by applying the measured DC offset of the ith frame to the (i+1)th frame, as illustrated in FIG. 1.
FIG. 1 is a diagram illustrating a DC offset compensation interval at a receiving terminal in a wireless communication system according to the related art.
Referring to FIG. 1, the receiving terminal measures the average value of the DC offset of the ith frame during a downlink (DL) subframe 100. Thereafter, the receiving terminal may remove the DC offset of the (i+1)th frame by compensating the DC offset during a Transmit/receive Transition Gap (TTG) 120 by using the measured DC offset value.
As described above, if the receiving terminal compensates the DC offset on a frame basis, the frame for DC offset estimation and the frame for DC offset compensation must have a similar DC offset. That is, if an inter-frame DC offset change is significant, the receiving terminal may fail to remove the DC offset due to an inaccurate estimate of the DC offset of a DC offset compensation frame according to the inter-frame DC offset change.